To prevent food poisoning, consumers should avoid eating raw or undercooked shellfish, according to officials at the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia.

The recommendation comes from a report of the largest-to-date outbreak of food poisoning caused by the bacteria Vibrio parahaemolyticus in North America, which occurred last summer in the Pacific Northwest. More than 200 confirmed cases of the disease were reported in California, Oregon, Washington state and British Columbia, and all resulted from the consumption of contaminated raw or undercooked shellfish, particularly oysters.

Symptoms of the disease generally appear within 15 hours of exposure, and consist of a mild to moderate stomach upset, which lasts for about 3 days. But the infection can be severe in patients with underlying medical conditions.

Morbidity and Mortality Weekly Report June 12, 1998;47:457-462.

COMMENT: My dietary guidelines call for exclusion of all shellfish and pork. The major concern is a risk of infection. Most of the animals are scavenger animals and harbor organisms which are frequently difficult, if not impossible, to kill with ordinary cooking methods. I believe that we will find more and more science like this CDC advice to back up my recommendation .